Actually we do know. They come from homes where a parent will abuse (physical and verbal) and neglect them. This has a direct impact on brain development and the ability to self regulate. When you hit a two year old, you’re putting them in stress mode. Not healthy for a developing brain. This isn’t rocket science. It’s really not their fault but at the same time it’s not fair for them to be disrupting other peoples education. In reality those parents need to be educated and those patterns of abuse need to be broken but saying you’re a shit parent has a condescending tone- not sure what program would address this.